Induction conveyor

ABSTRACT

An article induction system for preparing a stream of articles, such as mail parcels, for processing employs a series of conveyors operating under control of a controller for feeding articles to an operator at a cull belt at an optimal paced rate. The article induction system includes a destacking section, a separation and alignment section, a buffer section and a culling section manned by an operator. A controller controls the speed of each component based on measurements provided by sensors so as to feed articles to the operator at a desired paced rate.

RELATED APPLICATIONS

The present invention claims priority to U.S. Provisional PatentApplication No. 61/931,961, filed Jan. 27, 2014, entitled “InductionConveyor”, the contents of which are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the field of power-driven conveyors.More particularly, the present invention relates to an inductionconveyor that prepares conveyed articles for sorting using a sorter orfor another process.

BACKGROUND OF THE INVENTION

In mail processing systems and other applications involving processingof articles, it is often necessary to singulate articles into a singlefile stream, properly orient the articles, and space the articles priorto sorting the articles using an automated sorter. There are two currentapproaches to converting a bulk flow of articles, such as parcels, ontoa conveyor sortation system for sorting or otherwise processing: manualinduction and automatic induction.

Manual induction requires a worker to manually select, orient, and placean individual parcel on a conveyor. The parcel can be placed directly onthe sorter or on a variety of different types of inductions whichtransition the parcel onto the sorter.

Automatic induction uses automation to automatically convert bulk flowof parcels into a single file stream to feed a sorter without anoperator. If the stream is not appropriate for sortation, mechanical orelectrical devices are used to reject, recirculate, or remove theinappropriate articles from the flow. Inappropriate flow for sortationmay contain doubles, inadequate gapping, and non-conveyable items. Bulkflows of residential mail traditionally contain a high percentage ofbags, soft goods, and envelopes that do not perform well on currentautomation

SUMMARY OF THE INVENTION

A system and method for preparing a stream of articles, such as mailparcels, for processing employs a buffer for feeding articles to anoperator at an optimal paced rate. The article induction system includesa destacking section, a separation and alignment section, a buffersection and a culling section manned by an operator. A controllercontrols the speed of each component based on measurements provided bysensors so as to feed articles to the operator at a desired paced rate.

According to one aspect, a method of preparing a stream of articles forprocessing comprises the steps of singulating the articles using asingulating conveyor for form a series of singulated articles, bufferingthe series of singulated articles using a buffer; to form a series ofbuffered articles and passing articles from the buffer to an operator ata selected paced rate.

According to another aspect, a method of processing a series of articlescomprises the steps of singulating the series of articles, regulatingthe speed of each article in the series of articles and passing anarticle to a cull belt manned by an operator at a selected paced rate.

According to still another aspect, an induction conveyor systemcomprises a destacker for destacking articles operating at a destackingspeed, a singulating conveyor for receiving product from the destackerand singulating the product, the singulating conveyor operating at asingulating speed, an aligning conveyor for receiving singulated productfrom the singulating conveyor and aligning the product, the aligningconveyor operating at an aligning speed, a buffer for receiving thealigned product, buffering the aligned product and releasing the productto a cull belt, a cull belt for conveying product past an operator at aselected paced rate and a controller for controlling the destackingspeed, the singulating speed and the aligning speed based onmeasurements of the product by a plurality of sensors.

According to yet another aspect, an induction conveyor system comprisesa buffer conveyor for receiving and buffering articles, a cull belt forconveying the articles past an operator at a selected paced rate, anarray of sensors at interface between the buffer and cull belt and acontroller for controlling a release of an article from the buffer tothe cull belt based on a measurement from the array of sensors.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an overhead view of an article induction system of anillustrative embodiment of the invention;

FIG. 2 is a close up view of the first second of the article handlingsystem of FIG. 1;

FIG. 3 is a close-up overhead view of an embodiment of the separator ofthe induction system of FIG. 1;

FIG. 4 is an overhead view of an embodiment of the centering conveyor ofthe separator shown in FIG. 3;

FIG. 5 is a top view of the aligning conveyor of the separator shown inFIG. 3;

FIG. 6 shows a portion of an aligning conveyor belt in the separator ofFIG. 3;

FIG. 7 is another top view of an embodiment of the aligning conveyor inthe separation region of FIG. 3;

FIG. 8 is an alternate embodiment of a centering conveyor;

FIG. 9 is an alternate embodiment of an aligning conveyor;

FIG. 10 is an overhead view of the buffer of the article inductionsystem of FIG. 1;

FIG. 11 illustrates a portion of an embodiment of the buffer of thearticle induction system of FIG. 1;

FIG. 12 is an overhead view of the cull belt and discharge end of thebuffer of the article induction system of FIG. 1;

FIG. 13 illustrates the placement of sensors on the cull belt accordingto one embodiment of the invention;

FIG. 14 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to an embodiment of the invention;

FIG. 15 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention;

FIG. 16 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention;

FIG. 17 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention;

FIG. 18 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention;

FIG. 19 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention; and

FIG. 20 is a flow chart diagramming a control process for the articleinduction system of FIG. 1 according to another embodiment of theinvention.

DETAILED DESCRIPTION

A hybrid approach to preparing articles, such as parcels, forprocessing, uses an article induction system that comprises acombination of automated technology and an operator to prepare thearticles. The article induction system includes a buffer for regulatingthe articles prior to releasing the articles to an operator at aselected paced rate. The approach is especially beneficial whenprocessing bulk flows of residential mail, which traditionally containsa high percentage of bags, soft goods, and envelopes that do not performwell on current automation. The current system and method provideshigher productivity relative to the prior manual methods of induction.The invention will be described below relative to certain illustrativeembodiments, though those skilled in the art will recognize that theinvention is not limited to the illustrative embodiments.

FIG. 1 is an overhead schematic view of a product induction system 10 ofan illustrative embodiment of the invention. The illustrative system 10includes a first section 20 for depositing articles onto the inductionsystem, a separator 30 in a second section, a buffer in a third section40, and a culler manned by an operator 52 in a fourth section 50.

The product induction system includes a control system 70 forcontrolling the different components. The illustrative control systemcontrols the speed of each component so as to feed articles to theoperator 52 at a desired paced rate. Each component may operate at astandard speed, for example, delivering between about 3,000 and about5,000 parcels per hour to the operator, or another paced rate, and thespeed may adjust depending on certain conditions. The separator 30singulates product and feeds the product to the buffer 40, while thecontrol system 70 modulates conditions to keep the buffer 40 full orsubstantially full. The control system 70 also includes release logicfor determining when to release articles to the operator 52 in thefourth section 50 from the buffer in the third section 40. Preferably,the control system passes articles to an operator at an optimal selectedpaced rate, generally between about 3,000 and about 5,000 articles perhour, though the paced rate may vary depending on conditions. The pacedrate may be set by an operator, and may be changed. The paced rate maybe measured based on the distance between the front of a lead article tothe front of a trailing package, based on the gap between the trailingend of a package and the front of the next package, or through anysuitable means known in the art.

Referring to FIG. 2, the illustrative first section 20 comprises anunloader (not shown) and an incline conveyor 25 with a hopper 22 fordestacking conveyed articles. The open hopper 22 provides easy accessfor manual unloading of the product into the hopper from which theincline conveyor 25 ascends. The unloader may be a bulk conveyor forconveying articles towards the hopper 22. The unloader preferablyinterfaces with different styles of pallet and parcel unloading devices.The bulk conveyor may be a modular plastic bell, such as the S400 flattop belt from Intralox LLC, of Harahan, La., or another suitableconveyor driven by a motor in a conventional manner. The bulk conveyormay include side guards. The bulk conveyor may incline, or includes asection that inclines. Alternatively, an operator may dump a containerof articles into the hopper to load the incline conveyor.

The first section 20 provides a waterfall transition from the bulkconveyor to the incline conveyor 25 to assist in de-stacking theconveyed articles.

The incline conveyor 25 receives product from the unloader and beginsthe process of converting a three-dimensional flow of articles to atwo-dimensional flow of articles. The incline conveyor 25 also regulatesthe rate of flow of the articles.

The incline conveyor 25 may be configured to facilitate destacking ofarticles. In one embodiment, the incline conveyor 25 is a modularplastic belt incline conveyor formed by a pattern of flat top modules,such as the S1400 flat top units available from Intralox, LLC, andfriction top modules, such as the series 1400 friction top modular unitsfrom Intralox, LLC. The illustrative belt comprises a pattern of fifteenrows of flat top modules followed by three rows of friction top modulesinterspersed between the flat top modules. The illustrative belt isabout 35 inches wide.

The incline conveyor 25 rises along the belt length to assist indestacking stacked articles. In one embodiment, the incline conveyor 25rises between about 25° and about 35°, to allow product stacked on topof each other to slip off of one another.

A motor 252 drives the incline conveyor 25.

The incline conveyor includes sensors 254, 255, such as Bannerretro-reflective photoelectric cells, for monitoring product on the belt25. The controller 70 controls the motor 252 based on information fromthe sensors 254, 255 and other sources, such as other sensors in thesystem 10. The first sensor 254 is located at the tail end of theincline conveyor 25 to detect product placed on the conveyor. Controllogic may control the operation of the incline conveyor 25 based oninformation from the first sensor 254. For example, if no product isdetected for a set amount of time, the motor 252 turns the inclineconveyor 25 off. When the first sensor 254 is blocked, indicating thepresence of product on the incline conveyor 25, the control logicsignals the motor 252 to start automatically.

The head sensor 255 monitors product flow. In one application, if thehead sensor 255 is blocked by a period longer than a set amount, such asthree seconds, indicating an overflow condition, the motor 252 reducesthe speed of the incline conveyor 25 by up to 50% to slow down theproduct flow.

In another embodiment, the operation of the incline conveyor depends onthe buffer 40. For example, the controls may signal the motor 252 tooperate the incline conveyor 25 when the buffer 40 is not full and-orsignal the motor 252 to stop the incline conveyor 25 when the buffer 40is full.

The induction system 10 may include any suitable device for performingan initial destacking of articles and is not limited to the illustrativeincline conveyor 25.

Product from the incline conveyor 25 passes onto a conveyor in thesecond section 30. The illustrative induction system 10 has a waterfalltransition from the incline conveyor 25 to the third section 30, anembodiment of which is shown in FIG. 3, though the invention is not solimited.

The illustrative separator in the third section 30 comprises a series ofconveyors that singulate conveyed articles. In the illustrativeembodiment, the separator 30 comprises a number of conveyor belts andoperating under control of the control system 70, which regulates thespeeds of the conveyor belts. The illustrative separator 30 includes acentering conveyor 310 for receiving articles from the incline conveyor25 and singulating the articles in a single file line towards thelateral center of the conveyor 310. An aligning conveyor 320 receivesthe singulated articles and aligns the articles against one side of theseparator 30.

The illustrative centering conveyor 310 comprises the ARB™ technologyavailable from Intralox, LLC of Harahan, La. A combination of 30°, 45°,and 60° ARB™ belts can be used to center parcels at different angles. Inthe embodiment shown in FIG. 3, the centering conveyor 310 comprises hastwo centering zones formed by a series of conveyor belts 311, 312,having rollers or other devices that push articles towards the lateralcenter of the centering conveyor. A motor 325 drives the first centeringbelt 311 and another motor 326 drives the second centering belt 312.Alternatively, the centering conveyor 310 may comprise one or more setsof opposing side-by-side belts.

The centering conveyor 310 includes a flow monitor 327, such as aphotoeye.

As shown in FIG. 4, one embodiment of a centering conveyor 310′comprises a first centering conveyor having two sets of opposing beltswith embedded rollers. The embedded rollers roll during conveyance,causing product to move towards the center of the opposing belts. Thecentering conveyor 310′ comprises a first belt 311′ comprising, 60°rollers, a second belt 312′ opposing the first belt 311′ comprising 30°rollers, a third belt 313′ in series downstream from the first beltcomprising 30° rollers and a fourth belt 314′ in series downstream fromthe second belt comprising 60° rollers. In the illustrative embodiment,the transition between the first belt 311′ and the third belt 313′ isstaggered from the transition between the second belt 312′ and fourthbelt 314′. The invention is not limited to such an illustrativeembodiment, and the centering conveyor may comprise any suitable number,arrangement and type of conveyor.

The illustrative centering conveyor 310′ employs Series 400 ARB™technology by Intralox, LLC. The centering conveyor is driven withsprockets and rides on carry strips. The illustrative conveyor bedcomprises activation rollers, which may be steel helix rollers for the60° nodules in belts 311′ and 314′ and Armor X plating for the 30°modules in belts 312′ and 313′. The embedded angled rollers protrudeabove and below the modules. The activation rollers cause the embeddedangled rollers to spin, causing product to move in the direction of theroller orientation (i.e., towards the center of the conveyor).

In one embodiment, the opposing belts 311′, 312′ and 313′, 314′ alsomove at different speeds in addition to the centering action created bythe roller angles. The speed differential creates torque on the conveyeditems, allowing side-by-side items to separate and form into a singleline in the center of the conveyor 310′.

The conveyor may also include side guards 318 to help contain items onthe belts.

Motors drive the conveyor belts 311′, 312′, 313′ and 314′ under thecontrol of the control system 70.

The centering conveyor 310 or 310′ feeds the stream of singulatedarticles to an aligning conveyor 320, which drives the stream ofarticles to one side, preferably the operator side. The aligningconveyor 320 has a lower elevation than the discharge end 319 of thecentering conveyor 310 to create a waterfall at the transition. The drophelps to de-stack any stacked articles, and reduce jams at thetransition.

As shown in FIGS. 5-7, the illustrative aligning conveyor 320 comprisestwo independently driven belts 322, 324. A narrow belt 324 on theoperator side opposes an article-pushing belt 322 for pushing articlestowards the narrow belt 324. The narrow belt 324 preferably runs at afaster speed than the article-pushing belt to help pull any connected orclumped articles apart. The illustrative narrow belt 324 comprises aten-inch wide belt formed of the Series 400 ARB™ 0° modular unitsavailable from Intralox, LLC, while the illustrative article-pushingbelt comprises a 26-inch wide belt formed of Series 400 ARB™ 45° lefthand modular units available from Intralox, LLC. As shown in FIG. 6, thenarrow belt 324 includes rollers 3241 oriented at 0° relative to thedirection of travel and the pushing belt 322 includes rollers 3221oriented at 45° relative to the direction of travel for pushing conveyedarticles towards the narrow belt 324. Items 280 leaving the aligningconveyor 230 will be justified to a side wall 321 of the conveyor.

The overall speed of the aligning conveyor 320 is faster than thecentering conveyor 310. In one embodiment, the speed of the articlesdoubles between the centering conveyor 310 and the aligning conveyor 320to provide additional separation of conveyed articles.

As shown in FIG. 7, the aligning conveyor includes two sensors formonitoring the conveyed items. The illustrative embodiment comprises twoBanner retro-reflective photoelectric cells 328, 329. The first sensor328 detects product flow. If the sensor 328 detects a backup, forexample, if the sensor is blocked for more than three seconds, thecontrol logic 70 signals the motors 332, 334 to reduce the speed of thealigning conveyor 320 by a selected amount, such as 50% of normaloperating speed. The control logic 70 may also instruct the upstreamconveyors 25 and 310 to reduce speed based on a blockage signal from thesensor 328. The second sensor 329, located at the discharge end of thealigning conveyor 320, senses the presence of product at the discharge.The control logic 70 uses the signal from the second sensor 329 toinitiate operation of the buffer conveyor 40, as described below.

As shown in FIGS. 8 and 9, the separator 30 can alternatively form twostreams of articles, each justified against a side of the separator.FIG. 8 illustrates a double centering conveyor 3100 and FIG. 9illustrates a double aligning conveyor 3200.

Referring to FIGS. 1, 10 and 11, downstream from the separator 30, thebuffer 40 regulates the flow of articles between the separator 30 andthe operator 52. The buffer 40 receives articles from the separator 30and discharges articles to an operator at the cull belt in section 50 ata suitable paced rate. For example, the separator 30 may haveinstantaneous speeds of up to about 10,000 parcels per hour, while theoperator performs optimally with a steady flow of approximately 4,000parcels per hour as the paced rate. The buffer 40 regulates the flow toprovide an optimal, steady flow rate for the operator. The buffer 40 mayalso pull apart and declump multiple articles that are clumped togetheras a single item. The buffer 40 releases articles to the cull belt 50 ata paced rate that is optimal for the operator 52.

The illustrative buffer 40 comprises a motorized drive roller conveyorformed twelve drive roller zones 410 a-410 l in series. Each zonecomprises five consecutive rollers 411 controlled together. A driveroller 412, illustrated as the third roller in each set, is powered anddrives the other rollers in the set.

Sensors in each zone detect product on the buffer 40. The illustrativebuffer includes five separate sensors in each zone to detect product.The sensors are in the form of a photoelectric cell bar 460, shown inFIG. 11. Each bar has five separate diffused photoelectric sensors. Theblockage of any one of the sensors indicates the presence of product inthe corresponding zone. In the illustrative embodiment, thephotoelectric cell bar 460 is located between the drive roller 412(roller #3) and an adjacent roller 411 (roller #4) in each zone.

The buffer 40 allows pauses or slow down of operation by a cullingoperator 52 without affecting the flow of singulated product fromupstream conveyors. The buffer 40 discharges product to the cull belt510 at a selected paced rate, determined by the control logic 70.

The buffer 40 also includes a “buffer full” sensor 426 and a “bufferempty” sensor 428 for detecting the presence of product on the buffer40.

The last buffer zone 410 l releases articles to the fourth section 50 ofthe induction conveyor. The release of the articles from the buffer tothe fourth section is controlled by the controller 70 based on certainconditions, as described below.

The controller may control the speed of each zone of the buffer tofacilitate presentation of the articles to the cull belt 510. Forexample, one control technique involves setting the first several bufferzones 410 a-410 e at a high speed to pull the product away from thealignment belt after the alignment belt discharges the product onto thefirst buffer zone 410 a. In one embodiment, the rollers in the firstseveral buffer zones 410 a-410 e are set to a speed of between about 300and about 400 feet per minute, and preferably between about 350 andabout 370 feet per minute and more preferably at about 360 feet perminute to pass product along. In the next couple of zones 410 f and 410g, the speed of the rollers (or other conveyor in the buffer zone) isreduced significantly so that accelerations may be subsequentlyintroduced. In one embodiment, the conveyance speed is halved, tobetween about 150 and about 200 feet per minute and preferably tobetween about 175 and about 185 feet per minute and more preferably toabout 180 feet per minute for these intermediate zones. In the next twobuffer zones 410 h and 410 i, the conveyance speed is increased. Thespeed increase facilitates destacking and singulations, especially withflat articles. For example, in one embodiment, the speed is increased tobetween about 210 feet per minute and about 270 feet per minute,preferably between 230 and about 250 feet per minute and more preferablyabout 240 feet per minute. The buffer again increases the speed ofconveyance in the next two zones 410 j and 410 k to facilitate furtherdestacking and singulation. For example, the speed may be increased tobetween about 300 and about 400 feet per minute, and preferably betweenabout 350 and about 370 feet per minute and more preferably to about 360feet per minute to pass product along to the final buffer zone 410 l. Inthe final buffer zone 410 l, product can be brought in at a full rateand released to the cull belt at a reduced rate. For example, the finalbuffer zone 410 l may initially convey at a speed of between about 300and about 400 feet per minute, and preferably between about 350 andabout 370 feet per minute and more preferably at about 360 feet perminute and reduce the speed by half (to between about 150 and about 200feet per minute) for release to the cull belt.

The cull belt 510 in the fourth section 50 is the working belt for anoperator 52 to remove non-conveyable articles, oversized and-or damageditems. The operator may also manually declump parcels and smooth outlabels on soft parcels. The illustrative cull belt, shown FIG. 12,comprises a single conveyor belt formed of S1000 modules from Intralox,LLC with free spinning rollers to allow low pressure accumulation,though any suitable conveyor technology may be used. A motor 520 drivesthe cull belt under the control of the controller 70.

As shown in FIG. 13, the cull belt 510 includes sensors for monitoringproduct flow on the cull belt. In the illustrative embodiment, the cullbelt includes three sensors to detect backup. A head sensor 542 detectsproduct jam. If the reading from the sensor indicates a jam, the controllogic stops the cull belt 510 and upstream conveyors, while continuingto run the downstream conveyors in the subsequent sorting system.

Middle sensors 544, 546 are used to stop product from being dischargedfrom the buffer 40 in the event that multiple products enter the cullbelt 510. If the middle sensors 544, 546 are blocked for more than apredetermined amount of time, for example, one second, the control logicsignals the buffer conveyor 40 to pause from releasing the next productuntil the sensor is unblocked for at least a set amount of time.

The interface between the buffer 40 and the cull belt 510 includes anarray of sensors 461 for monitoring product. The sensors 461 may be aseries of photoeyes extending laterally across the width of the bufferat the transfer end of the buffer 40.

The product induction system 10 employs control techniques to provideoptimal performance. The control techniques can be used independently ortogether.

A first control technique, diagrammed in FIG. 14, regulates the speedand flow of the articles in the separator 30 to reduce the number ofside by side articles. The first control technique controls the motors252, 325 and 326 based on data front the sensors. In step 1410, thesensor 327 detects a large burst of product, as measured by the amountof time the sensor 327 is blocked. For example, if the sensor 327 isblocked by more than three seconds, indicating that articles are clumpedtogether, the motors 252, 325 and—or 326 slow down in step 1420. If noburst is detected, the motors continue to operate normally in step 1430.The aligner conveyor 320 may continue operating at standard speed.

The slowed down conveyors may return to full speed when the sensor 327is unblocked for a certain amount of time, such as three seconds. If thesensor is unblocked 327 by a long time, such as ten minutes, one or moreof the conveyors may enter sleep mode. The conveyors awake and return tonormal speeds when the incline conveyor sensor 255 senses productthrough a cascade start.

FIG. 15 illustrates another control technique using a sensor. If sensor328 in the aligning conveyor 320 detects a burst of product in step1510, then the motors 252, 325, 326, 332 and 334 slow down in step 1520.If the sensor does not detect a burst, the motors operate normally instep 1530.

The buffer full sensor 426 and buffer empty sensor 428 may be used toregulate the speed of the separator 30 and incline conveyor 25. Forexample, at a standard operating speed, the inclined conveyor 25 iscapable of delivering between 3000 and 4000 parcels per hour, preferablyabout 3600 parcels. If the empty buffer sensor 438 is clear for morethan a specified period of time, such as one second, the inclineconveyor 25 speeds up. If the buffer is full, indicated by the fullbutter sensor 426, the incline conveyor may slow down or temporarilyhalt. FIG. 16 illustrates a technique for controlling the inductionconveyor based on the buffer empty sensor. The control logic controlsthe speed of the separator 30 as the buffer 40 fills and empties. Forexample, in step 1610, the buffer empty sensor 428 senses that thebuffer is low if the sensor is unblocked. In response, the control logicincreases the speed of motors 252, 325, 326, 332 and—or 334 in step 1620to fill the buffer 40. If the sensor does not detect a low buffer, themotors run as normal in step 1630.

FIG. 17 illustrates the steps taken to control the buffer based on asignal from the buffer full sensor 426. If the buffer full sensor 426 isblocked, indicating that the buffer is full or almost full in step 1710,the controls slow down the motors 252, 325, 326, 332 and—or 334 in step1720 to decrease the number of articles passed onto the buffer 40. Ifthe detection step in step 1710 indicates the absence of blockage, themotors run as normal in step 1730.

FIG. 18 illustrates a control technique used to break up a group ofmultiple articles flowing as a single item in the buffer 40. If a sensor460 in a particular buffer zone 410 senses a clump of articles, forexample if a photoeye 460 is blocked by longer than necessary for asingle article in step 1810, the controls signal the motor for thedownstream adjacent buffer zone to pause and restart to declump thearticles in step 1820. If the sensor detects no clumping, the motor andbuffer zone run as normal.

For example, conveyed parcels in the mail processing industry arenormally expected to block a photoeye for a preset amount of time. Forexample, a 12″ box moving 240 feet per minute will block the photoeyefor 0.25 seconds. If the photoeye is blocked for longer than 0.25seconds, there is a high likelihood that two parcels are movingtogether. Once the photoeye in a buffer zone is blocked for longer than0.25 seconds, the controls pause the buffer zone below the photoeye. Thefirst box, already advanced to the next zone, should pull apart andcreate a gap between parcels.

The longest product may be longer than one buffer zone, which requiresmultiple conveyors working together to move the product.

FIG. 19 illustrates the steps involved in controlling the release ofarticles from the buffer 40 to the cull belt 510 for processing by theoperator 52. For example, if multiple items are detected and released atthe same time, the controller 70 may increase the manual processing timefor the operator by delaying the release of an item front the buffer tothe cull belt. In step 1910, the array of sensors 461 at the dischargeof the buffer is monitored. If more than one sensor in the zone isblocked in step 1920, indicating either multiple items clumped togetheror a large parcel in the wrong orientation, the controls extend thedelay before activating the motor of the last buffer zone to release thenext item to the cull belt in step 1920. The delay allows the operatormore time to manage the flow of product. If multiple sensors are notblocked, the buffer releases the next parcel onto the cull belt with astandard delay in step 1930.

FIG. 20 illustrates another method for delaying the release of productsonto the cull belt 510 if desired by the operator 52 to provide moretime to manage the products on the cull belt. In step 2010, the sensors461 between the buffer 40 and cull belt 510 are blocked for more than aselected period of time, such as one second. If the sensors 461 areblocked for more than the selected period of time, the buffer release ispaused until the sensors are unblocked in step 2020. The sensors 461 maybe blocked manually by the operator or by the operator holding backmultiple articles so that the articles block the sensors. The pause ofthe buffer release in step 2020 allows the operator more time to performthe cull function when necessary. If the sensors are not blocked, thebuffer 40 releases the next article to the cull belt 510 with thestandard delay in step 2030.

Preferably, the buffer passes articles to the operator and the operatorprocesses the articles at the cull belt with a spacing that matches thespacing of carriers in a downstream sorter.

The head sensor on the cull belt may be used to detect a product jam. Ifthe head sensor is blocked by more than a selected amount of time, suchas three seconds, the cull belt and all upstream conveyors stop or slowdown.

The invention has been described relative to certain illustrativeembodiments, though those skilled in the art will recognize thatmodifications may be made without departing from the scope of theinvention.

What is claimed is:
 1. A method of preparing a stream of articles forprocessing, comprising the steps of: singulating the articles using asingulating conveyor to form a series of singulated articles; aligningthe series of singulated articles using an aligning conveyor comprisinga narrow belt on a first side and an article pushing belt opposing thenarrow belt for pushing articles towards the narrow belt; buffering theseries of singulated articles using a buffer to form a series ofbuffered articles; and passing the series of buffered articles from thebuffer to an operator at a selected paced rate.
 2. A method of preparinga stream of articles for processing, comprising the steps of:singulating the articles using a singulating conveyor to form a seriesof singulated articles; buffering the series of singulated articlesusing a buffer to form a series of buffered articles; and passing theseries of buffered articles from the buffer to a cull belt manned by anoperator at a selected paced rate based on a measurement from an arrayof sensors at an interface between the buffer and the cull belt.
 3. Themethod of claim 2, further comprising the step of adjusting a speed ofthe singulating conveyor based on a fullness measurement of the buffer.4. The method of claim 2, further comprising the step of releasing anarticle from the buffer conveyor to the cull belt when signaled by acontroller.